1. Field of the Invention
The present invention relates to an ink jet head base body having arranged thereon a number of electricity-heat converters on a support member (substrate) and an ink jet head using said base body, as well as a method for fabricating said base body and said head.
2. Related Background Art
Typically, among ink jet heads, the construction of an ink jet head of the type where a number of electricity-heat converters are provided on a substrate is provided on the substrate 1 with a heat generating resistance layer 2 containing heat generating resistors 2a as heat energy generators for generating heat energy to be acted on the liquid and an electrode layer 3 for applying voltage to said heat generating resistors, as shown in FIGS. 3A and 3B. Also, a protective layer 4 is provided, as required, on the electricity-heat converters comprised of the heat generating resistance layer 2 and the electrode layer 3.
An ink jet head is constructed in such a way as to bond a ceiling plate having grooves onto such substrate, each groove serving to form an orifice (discharge opening) 7 through which liquid is discharged and a liquid channel 6 communicating with said orifice 7 and provided at a site corresponding to said heat generating resistor 2a. Conventionally, an ink jet head was obtained by preparing electricity-heat converters corresponding to a plurality of ink jet heads on an Si wafer which is a substrate, and cutting and separating the Si wafer after bonding such a ceiling plate to the Si wafer.
Herein, a base body 8 can be obtained by laminating at least an electrode layer 3 and a heat generating resistance layer 2 on a substrate 1, patterning them into a predetermined shape, and forming heat generating resistors 2a electrically connected to a pair of electrodes 3a, 3b spaced apart a predetermined interval, as shown in FIGS. 4A and 4B.
And the electrode layer 3 and the heat generating resistance layer 2 are formed by thin film forming technology such as sputtering which may be utilized in the semiconductor fields.
On the other hand, such base bodies have been made in larger sizes in recent years, aiming at reducing the costs due to improvement of the through-put. Along with the larger base body, the substrate is changed in shape from round to rectangular substrate. That is, the round Si substrate currently available is limited in size up to as large as 8 inches in diameter, because if an integral-type ink jet head having the print width beyond that limit size is to be fabricated, the substrate is obliged to be a rectangular substrate which is fabricated by cutting an Si ingot in regular grain. Also, if the substrate is made larger in this way, there is often seen a dispersion in quality such as film thickness dispersion in the above-mentioned thin film forming technology.
Thus, in order to check and manage a variety of qualities in the manufacturing process of such base plates 8, the manufacturers have been involved in providing monitors such as a specific resistance measuring monitor 1d.sub.1, a film thickness measuring monitor 1d.sub.2, and an adhesion strength measuring monitor 1d.sub.3 on a part of the base body 8 on which a base body portion 1a corresponding to one of a plurality of ink jet heads is disposed, to measure properties of the base body such as the film thickness of each layer, resistance of heat generating resistance layer, and film adhesion strength, as shown in FIG. 2.
However, when the substrate is rectangular, because by cutting a rectangular base body, as previously described, monitors will be disposed in the effective portion, thus reducing the number of pieces to be taken.
Also, to enhance the print quality, it is necessary to arrange more monitors for the quality management as described above as the substrate is larger, and as a greater number of monitors are provided, the number of ink jet heads produced per substrate is further reduced, resulting in an increase in cost. If the monitor is reduced in size, the measurement may become impossible, or the measurement accuracy may be remarkably degraded, rather resulting in the lower yield.